A related-art in-vehicle cooling device is configured to cool, with use of a traveling air flow, electrical equipment such as a transformer and a reactor mounted on a vehicle. The transformer is installed at a lower portion of the vehicle, and the cooling device is mounted horizontally adjacent to the transformer.
The in-vehicle cooling device includes cooling pipes through which a cooling medium flows, and a header for fixing the cooling pipes, the header having a flow path of the cooling medium, the flow path being formed therein. Each of the cooling pipes is curved into a U-shape or a rectangular U-shape, and both ends thereof are fixed to the header. A plurality of cooling pipes are installed on the same plane that is orthogonal to the traveling direction, to thereby form a cooling pipe group. A plurality of cooling pipe groups are further arranged to overlap with each other in the traveling direction. The cooling pipe groups and a communication passage are mounted on the header by welding and the like. The header has mounting positions for mounting the cooling pipes at even intervals in each of a lateral direction and a vertical direction.
The cooling medium is fed from a vehicle transformer main body through a pipe to enter the communication passage, and passes from the header through the cooling pipe group to flow into the header again. Then, the cooling medium passes from the header through the communication passage to return to the vehicle transformer main body again. When the cooling medium flows through the cooling pipe group, due to the heat transfer in the natural convection at the outer surface of the cooling pipe group and in the forced convection caused when the traveling air flow passes along the surface of the cooling pipe group, heat of the cooling medium is exchanged with the outside air, and thus the cooling medium is cooled. In this case, in order to promote the cooling effect by the forced convection heat transfer, the cooling device has been installed on the vehicle side portion at which the traveling airflow rate is large. When such a railroad vehicle travels, a traveling air flow blows in a direction opposite to the vehicle traveling direction in the vicinity of the reactor. This traveling air flow removes the generated heat to cool the winding.